1. Field of the Invention
The present invention relates to a mobile robot, which automatically moves about a room, and more particularly, to a mobile robot having a vision camera to recognize its location and to avoid collision with obstacles in the room. The present invention also relates to a course adjusting method for the mobile robot.
2. Description of the Related Art
Generally, a mobile robot has a power source and a sensor mounted in its body, and thus can automatically run about a given area without an external power supply or manipulation. There are two main types of mobile robots that are used inside a house: robots that clean the rooms of the house; and robots that guard the house from possible intruders.
The conventional mobile robot uses a random motion method, by which the mobile robot moves in a random direction without recognizing its location, repeatedly shifting its direction whenever it encounters obstacles, such as a wall, table, etc.
Such a conventional mobile robot includes a running device for moving the mobile robot about a room, an obstacle detecting device for detecting the presence of an obstacle, such as a wall, table, etc., a controlling portion for adjusting an orientation of the mobile robot by controlling the running device and the obstacle detecting device, and a power supply for storing and supplying the power to the respective devices.
The running device can be a wheel-type device that employs a servo-motor or stepping motor to rotate a plurality of wheels and move the mobile robot, a caterpillar-type device that uses an endless track, or a joint-type device that uses a plurality of legs. Among these types of devices, the wheel-type running device is most widely used.
The obstacle detecting device detects obstacles, such as a wall, table, etc., with an ultrasonic sensor or laser sensor, and sends out a corresponding signal to the controlling portion. The sensor of the obstacle detecting device is preferably mounted on a front side of the mobile robot in parallel with a running surface, so as to detect more accurately the obstacle located in the running path.
The controlling portion includes a microprocessor and memory mounted thereon for controlling general operations of the mobile robot, such as sending out a start command to the running device, controlling movement of the running device to avoid an obstacle in accordance with the signals received from the obstacle detecting device and an internal, prefurnished program, and charging the power supply with electricity when it determines that the power level is below a predetermined value.
The power supply supplies power for operating various parts of the mobile robot, such as the motor, which rotates the wheels of the running device, the sensor, which detects the presence of any obstacles, and the control portion, etc. The power supply usually is a storage battery, enabling the mobile robot to operate for a predetermined period of time without connection to an external power source.
The operation of the mobile robot constructed as above will be described in detail below.
First, when the mobile robot receives a start command, the controlling portion sends out a running command and corresponding sensing signal to the running device and the obstacle detecting device, respectively. In response to the signal from the controlling portion, the running device runs in a certain direction by driving the motor. At this time, by operating the sensor, the obstacle detecting device sends out a sensing signal to the controlling portion. During operation of the mobile robot, when the sensor senses the presence of an obstacle within a predetermined distance range of the robot, the controlling portion sends out a command to the running device to shift the path or running direction of the mobile robot. Then the running device resumes running of the mobile robot. Whenever the mobile robot encounters an obstacle, the running direction of the mobile robot is altered by the processes described above. That is, the mobile robot runs according to its initial position and the locations of the obstacles, drawing a random track as shown in FIG. 1.
Such a random motion mobile robot is found to be inefficient when running in a limited area, since it runs on a random track. Another drawback of the random motion mobile robot is that it repeatedly travels across the same area.
The ultrasonic sensor of the conventional obstacle detecting device includes an ultrasonic emitting portion for emitting ultrasound waves, and an ultrasonic receiving portion for receiving reflective ultrasound waves from the obstacle. By measuring a time gap between ultrasound emission and reflective ultrasound receipt, the controlling portion calculates a distance from the mobile robot to the obstacle, and accordingly controls the motor of the mobile robot to avoid the obstacle.
Although the conventional obstacle detecting device and method thereof can measure the distance from the mobile robot to the obstacle, the same cannot properly deal with the obstacles according to the status of the obstacle, since it is impossible to obtain precise information about the status of the obstacle, such as the shape of the obstacle, or the like. Accordingly, it is impossible for the mobile robot to determine whether to pass or avoid the obstacle.
The mobile robot is required to keep a predetermined orientation in order to perform a cleaning or guarding operation more efficiently. For this, it is necessary to periodically check whether the mobile robot is running along the right course and to adjust the orientation of the mobile robot, if it is determined that the mobile robot has deviated off course.
In order to ensure that the mobile robot runs on the right course, the conventional mobile robot uses a guide tape or a wall of a room as a reference.
When using the guide tape, which is attached to the floor, the mobile robot checks for the guide tape by using a photo-sensor or a magnetic sensor. The mobile robot runs along the guide tape. The relative location of the guide tape with respect to the sensor determines whether the mobile robot is on the right course or not.
When using the wall of the room as a reference, whether the mobile robot moves along the right course or not is determined according to the distance of the mobile robot from the wall, as detected by a sensor, such as ultrasonic sensor, etc. Depending on the distance between the mobile robot and the wall, the mobile robot will adjust its orientation.
While these ways to adjust the course of the mobile robot, i.e., using the guide tape or wall as a reference, can be useful when controlling the running of the mobile robot, they are hardly applicable to a mobile robot that recognizes its location using a vision camera. That is, separately providing the guide tape or the ultrasonic sensor to the mobile robot that recognizes its location by vision camera, just to determine whether to adjust the orientation of the mobile robot or not, causes disadvantages, such as complicating manufacturing processes and increasing manufacturing costs.
The present invention has been made to overcome the above-mentioned problems of the related art. Accordingly, it is an object of the present invention to provide a mobile robot capable of efficiently running along a certain course while recognizing its location and avoiding repeat passes in the same area.
Another object of the present invention is to provide a mobile robot capable of determining whether to pass or avoid an obstacle in a running direction, based on information about a shape of the obstacle. Information on the obstacle""s shape is provided by an obstacle detecting device having a line laser and a vision camera.
Yet another object of the present invention is to provide a method for adjusting an orientation of the mobile robot, which recognizes its location by using a vision camera, according to a determination as to whether to maintain or shift the path.
The above objects are accomplished by a mobile robot according to the present invention. The mobile robot includes a running device for moving the mobile robot about a room, an obstacle detecting device for detecting a presence of an obstacle, a location recognizing device for recognizing a current location of the mobile robot, a controlling portion for controlling the running device, the obstacle detecting device and the location recognizing device, and a power supply for storing and supplying electricity to each of the devices and the controlling portion. The location recognizing device includes a first vision camera facing a ceiling of the room. The first vision camera recognizes a base mark on the ceiling. The location recognizing device further includes a first vision board for processing an image photographed by the first vision camera into data and transmitting the data to the controlling portion.
The obstacle detecting device includes a line laser for emitting a linear light beam toward the obstacle, a second vision camera for recognizing a reflective linear light beam from the obstacle, and a second vision board for processing image data captured by the second vision camera.
Further, the above objects are also accomplished by a mobile robot according to the present invention, including a running device for moving the mobile robot in a room, an obstacle detecting device for detecting a presence of an obstacle, a location recognizing device for recognizing a current location of the mobile robot, a controlling portion for controlling the running device, the obstacle detecting device and the location recognizing device, and a power supply for storing and supplying electricity to the running device, the obstacle detecting device, the location recognizing device and the controlling portion. The obstacle detecting device includes a line laser for emitting a linear light beam toward the obstacle, a second vision camera for recognizing a reflective linear light beam from the obstacle, and a second vision board for processing image data captured by the second vision camera.
The second vision camera includes a filter for exclusively recognizing the linear light beam from the line laser.
Further, the above objects are also accomplished by a method for adjusting a course or running route of a mobile robot. The mobile robot includes a running device for moving the mobile robot about a room, an obstacle detecting device for detecting a presence of an obstacle, a location recognizing device for recognizing a current location of the mobile robot, a controlling portion for controlling the running device, the obstacle detecting device and the location recognizing device, and a power supply for storing and supplying electricity to each of the devices and the controlling portion. The method includes photographing a base mark using a first vision camera of the location recognizing device and generating image data of the base mark using a first vision board, determining whether coordinates of the base mark, which are obtained by data processing of the controlling portion, match coordinates of a predetermined moving route, and controlling the running device to move the mobile robot in a direction by a corresponding distance to compensate for any deviation from the predetermined moving route, when the coordinates of the base mark do not match the coordinates of the predetermined moving route.
The mobile robot according to another preferred embodiment of the present invention further includes a vacuum cleaner which has a suction port for sucking in contaminants, a dust collecting portion for collecting the contaminants therein, and a motor driving portion for generating a suction force.